Enhanced NO₂ gas sensing performance of bare and Pd-loaded SnO₂ thick film sensors under UV-light irradiation at room temperature

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• 作者：Fahimeh Hooriabad Saboor^a ; ^bAuthor Vitae ; Taro Ueda^bAuthor Vitae ; Kai Kamada^bAuthor Vitae ; Takeo Hyodo^bAuthor Vitae ; Yadollah Mortazavi^a ; ^cAuthor Vitae ; Abbas Ali Khodadadi^aAuthor Vitae ; Yasuhiro Shimizu^b ; ^{shimizu@nagasaki-u.ac.jp" class="auth_mail" title="E-mail the corresponding author}Author Vitae
• 关键词：NO2 ; Gas sensor ; UV ; SnO2 ; Pd functionalization
• 刊名：Sensors & Actuators: B. Chemical
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：223
• 期：Complete
• 页码：429-439
• 全文大小：3188 K

文摘

NO₂ gas sensing performance of bare and Pd-loaded SnO₂ thick film sensors were measured under UV-light irradiation, using a UV-LED of 365 nm wavelength and light intensities ranging from 0 to 137 mW cm⁻² at room temperature (30 °C). Template free conventional and microwave-assisted hydrothermal methods were applied to synthesize SnO₂ powder with different specific surface areas and morphologies (rod-shape and nanoparticle). Two different Pd-loaded SnO₂ (0.03 and 0.1 wt%) powders were also prepared by a simple wet-impregnation method. XRD, FE-SEM/SEM, XPS, BET surface area and BJH pore size distribution measured with N₂ adsorption isotherms were utilized to characterize structural and morphological characteristics of all the samples. The results clearly confirmed that the presence of a low amount of Pd could effectively enhance the response value to 5 ppm NO₂ gas and shorten the recovery time under the UV-light irradiation so that the sensor loaded with 0.1 wt% Pd (0.1Pd_MH1_400 sensor) showed the largest improvement in response value (almost 11 times) and recovery time (around 27 s) compared with the bare SnO₂ sensor (MH1_400) at an UV-light intensity of 79 mW cm⁻². This enhancement is most likely due to the role of Pd in facilitating the sensing reactions via producing additional NO₂ adsorption sites on the SnO₂ surface. Moreover, in the present study, the SnO₂ sensor which was fabricated from as-synthesized, i.e. uncalcined, powder (MH1) showed the highest response (over 3000) compared with other sensors under an UV-light intensity of 7 mW cm⁻² with a recovery time of about 48 s. The drastic decrease in the resistance in air of this sensor under the UV-light irradiation may be a possible reason for the highest response value. It was also revealed that high NO₂ response could be achieved only at the optimum conditions of both the number of the NO₂ adsorption sites (optimum specific surface area) and the electron density in the bulk under the UV-light irradiation.